Composite video signals are widely used for multimedia devices, such as analog TV systems, DVD systems, etc. A composite video signal often combines on one wire video information needed to recreate a color picture, as well as line and frame synchronization pulses. For example, a Composite Video Broadcasting Signal (CVBS) includes a luminance component, one or more chrominance components, one or more horizontal synchronization (hSync) pulses and one or more vertical synchronization (vSync) pulses.
As shown in FIG. 1, an analog intermediate-frequency (IF) signal 102 is converted by a demodulator 104 to a CVBS 106 and an audio signal (not shown), where a CVBS decoder 110 processes the CVBS 106. Usually, the hSync pulses in the CVBS 106 can be used to generate a line lock clock which is used as a work clock for the CVBS decoder 110. The usage of the line lock clock may ensure that the quantity of sampling points at each line are the same so that luminance (Y) and chrominance (C) components of the CVBS 106 can be separated through subsequent filtering (e.g., using 2D and 3D comb filters).